Electrophotography – Image formation – Development
Reexamination Certificate
1999-09-29
2001-07-31
Royer, William J. (Department: 2852)
Electrophotography
Image formation
Development
C399S260000, C399S262000
Reexamination Certificate
active
06269234
ABSTRACT:
This invention relates to electrophotographic reproduction machines, and more particularly to all-in-one process cartridge for use in electrophotographic reproduction machines. Specifically this invention relates to such a cartridge with a positioning lock to enable a refill strategy.
Generally, the process of electrophotographic reproduction, as practiced in electrophotographic reproduction machines, includes charging a photoconductive member to a substantially uniform potential so as to sensitize the surface thereof. A charged portion of the surface of the photo conductive member is exposed at an exposure station to a light image of an original document to be reproduced. Typically, an original document to be reproduced is placed in registration, either manually or by means of an automatic document handler, on a platen for such exposure.
Exposing an image of an original document as such at the exposure station, records an electrostatic latent image of the original image onto the photoconductive member. The recorded latent image is subsequently developed using a development apparatus by bringing a charged dry or liquid developer material into contact with the latent image. Two component and single component developer materials are commonly used. A typical two-component dry developer material has magnetic carrier granules with fusible toner particles adhering triboelectrically thereto. A single component dry developer material typically including toner particles only can also be used. The toner image formed by such development is subsequently transferred at a transfer station onto a copy sheet fed to such transfer station, and on which the toner particles image is then heated and permanently fused so as to form a “hardcopy” of the original image.
It is well known to provide a number of the elements and components, of an electrophotographic reproduction machine, in the form of a customer or user replaceable unit (CRU). Typically such units are each formed as a cartridge that can be inserted or removed from the machine frame by a customer or user. Reproduction machines such as copiers and printers ordinarily include consumable materials such as toner, volume limiting components such as a waste toner container, and life cycle limiting components such as a photoreceptor and a cleaning device. Because these elements of the copying machine or printer must be replaced frequently, they are more likely to be incorporated into a replaceable cartridge as above.
There are therefore various types and sizes of cartridges, varying from single machine element cartridges such as a toner cartridge, to all-in-one electrophotographic toner image forming and transfer process cartridges. The design, particularly of an all-in-one cartridge can be very costly and complicated by a need to optimize the life cycles of different elements, as well as to integrate all the included elements, while not undermining the image quality. This is particularly true for all-in-one process cartridges to be used in a family of compact electrophotographic reproduction machines having different volume capacities and elements having different life cycles.
Customer replaceable units (CRUs) which may also be known as cartridges, i.e., process cartridges, are intended to be removed and replaced by a fairly untrained operator of the copy or printing machine. The removal of the CRU and the replacement with a new a CRU is intended to be a simple, easy task. Typically, CRU is replaced by first opening a cover or door and then sliding the CRU out of a cradle or location where the CRU fits within the machine. These CRUs are used to interact with the xerographic process and with the paper within the machine. Therefore, CRUs frequently need to be engaged into an operating position within the machine during the installation of the CRU. The CRU thus typically is slid or placed into the opening where it fits and then positioned into an operating arrangement within the printing machine. Typically, the used CRU must first be separated from the components with which it engages and then withdrawn from the printing machine. Similarly, a new replacement CRU must first be inserted into the machine and then interconnected with the operating portions of the printing machine. Such a typical CRU is in the form of a process cartridge.
In recent years, the replaceable print cartridge trend in small office/hone office/desktop printers and copiers has been all-in-one single component development cartridges. This is evident through a quick study of recent industry print cartridges. One reason for this trend could be ease of customer use. A customer has only to replace one cartridge to replace the entire xerographic engine of their printer/copier. No separate dry ink, charging system cartridges, waste toner tanks, etc. need to be dealt with.
These all-in-one cartridges typically have lives of 2000 to upwards of 25,000 prints. Cartridge life is usually terminated by an electronic customer replaceable unit monitor (CRUM), a low toner sensor, or when the cartridge simply runs out of toner (giving light prints or deletions). The life limiting constraint for these cartridges is new toner capacity. All of the other components usually have life left in them when the toner runs out. This is why the recycle/refurbish industry for print cartridges is so profitable.
A common measure of the ownership cost of a cartridge is to take its initial cost divided by its life. To drive down ownership cost, either the initial cost of the cartridge must be reduced or the life of the cartridge must be extended. Both of these activities have limits, however.
The easiest way to reduce the initial cost of a cartridge is by driving down the cost through redesign or through the use of less expensive materials. Sometimes this strategy can backfire and end up costing more in the long run through quality issues or implementation costs. Even if the costing down activities are beneficial, the amount of cost that can be squeezed out of a design has a limit. Another way to drive down initial cost is through including a recycling/refurbishing factor. However, there are costs associated with returning and remanufacturing a cartridge. As the costs of cartridges keep getting driven toward their lower limits, the recycling costs often start to approach or exceed the costs associated with building a new cartridge.
This leads one to conclude that the best way to reduce ownership cost is to extend the life of the cartridge. However, as mentioned, the life of the cartridge is usually limited by the amount of new toner in the cartridge. To extend life, space for more toner in the machine must be found as well as cost effective means of delivering that extra-toner to the developer roll. This is not always possible or cost effective.
Another strategy for reducing the ownership cost has been to “split” the cartridge. The most common split cartridge design is a photoreceptor cartridge and a developer cartridge. The advantage to this strategy is that the photoreceptor cartridge can be run until its first component fails. The developer cartridge is then the only cartridge affected by new toner capacity. The split therefore decreases the amount of cost that is effected by the new toner capacity. The disadvantages of this strategy are that splitting the cartridges is challenging (dirty); the cost of the cartridges still are high (the costly developer roll is still frequently replaced); and the customer must now change two cartridges.
Yet another strategy for reducing the ownership cost has been to employ a separate toner cartridge that mounts in the machine. Toiler is then delivered to the print cartridge from the toner cartridge. When the toner cartridge is empty, the customer replaces the toner cartridge, which does not contain a costly developer roll. The life of the print cartridge can then be extended until its first component fails. Disadvantages to this strategy again are: finding space within the machine to load an acceptable capacity toner cartridge; the costs associated with cleanly and effecti
Chiesa Daniel A.
Claessens Tom W.
Kurz Karl E.
Kepner Kevin R.
Royer William J.
Xerox Corporation
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